X-ray crystal structure studies will be undertaken on chemically-differet drugs which have clinical use or potential as agents against central nervous system pathologies. The structures of two new derivative/metabolites of carbamazepine (tegretol) will be investigated. These compounds have recently been reported to have anti-convulsant efficacies which make them potentially valuable clinical agents, and the comparison of their three-dimensional stereochemistries with other useful anti-epileptics should yield information about the molecular determinants of biological activity. The structure of leucine-enkephalin, in a crystal form which contains at least four separate and independent molecules in the asymmetric unit, will be studied. In addition, crystallization attempts will be carried out on some active and inactive synthetic analogues of enkephalins in order to determine molecular bases of opiate and analgesic characteristics. We shall also continue attempts to utilize the knowledge we have so far gathered on anticonvulsant stereochemistry to design and synthesize new antiepileptic drugs.